#include<stdio.h>

#define OFFSET ('a' - 'A')

char ch_up_low(char c);
int main(int argc, char *argv[])
{
	char c;
	char ans;
	scanf("%c", &c);
 	
	ans = ch_up_low(c);
	if(ans == '1'){
		printf("输入错误！\n");
		return -1;
	}

	printf("%c大小写转换后为：%c\n", c, ans);
	return 0;
}

char ch_up_low(char c){
	
	char res;
	if(c >= 'a' && c <= 'z'){
		res = c - OFFSET;
	}else if(c >= 'A' && c <= 'z'){
		res = c + OFFSET;
	}else{
		return '1';
	}
	return res;
}

